Ministers were today warned that they may face a parliamentary revolt over plans to make it easier for the attorney general to halt a prosecution on the grounds of national security.

MPs spoke out following yesterday's high court judgement saying the Serious Fraud Office was wrong to drop its criminal investigation into secret payments by the arms company BAE Systems to Saudi Arabia.

The government is now under pressure to reopen the investigation. But ministers are also being urged to drop a proposal in the draft constitutional renewal bill that could allow the attorney general to halt a prosecution like the BAE one without having to worry about the decision being challenged in the courts.

Downing Street has so far refused to comment on the BAE case, referring callers to the SFO. The SFO has said it is studying the judgment and considering the way forward.

Campaigners from two groups, the Campaign against the Arms Trade and Corner House Research, used the judicial review process to challenge the SFO's decision to halt the BAE investigation in December 2006.

But a draft bill published last month would give the attorney general the power to halt a prosecution of this kind on the grounds of national security. In theory an order of this kind would not be subject to judicial review, but experts are divided as to whether or not it could in practice be challenged.

David Winnick, a Labour backbencher and a member of the Commons home affairs select committee, said today: "In view of what has happened, and the ruling by the judges yesterday, I do not believe that it would be in the overall national interest for the attorney general to have such powers."

Speaking on BBC Radio 4's The World at One, Winnick said there was likely to be "unease" among many MPs about the plan. "There's bound to be more controversy if it is intended to go ahead," he said.

Nick Clegg, the Liberal Democrat leader, also urged the government to drop the plan to allow the attorney general to halt an investigation of this kind more easily.

"I am dismayed by the self-inflicted damage being wrought by this government's actions on Britain's standing in the world," Clegg said in a letter to the prime minister, in which he also renewed his call for an inquiry into how the BAE investigation was halted.

The Conservatives have so far not opposed the plans to change the powers of the attorney general, although Andrew Tyrie, a backbench Tory, said today that the party would want to discuss the matter again in the light of the BAE case.

Jack Straw, the justice secretary, published the draft constitutional renewal bill last month. It is undergoing pre-legislative scrutiny by a committee of MPs and peers, which means that legislation is unlikely to be passed until next year.

The Ministry of Justice would not speculate on whether the powers could be used to stop the BAE investigation in the event of its being reopened and still being ongoing at the time of the bill becoming law.

In a statement, the ministry said the bill would "clarify and make more transparent" the role of the attorney general.

The bill will stop the attorney general giving orders to the SFO and the Crown Prosecution Service in relation to individual cases.

But, crucially, there will be an exemption, saying the attorney general can intervene on the grounds of national security. This would make it easier for the attorney general to halt an investigation such as the BAE one.